Basically I get spam only users. All their posts are spam so I simply want to ban them & hard delete ALL their posts. I didn't found a way to easily do that.

I go to the user, I can ban him but then what? If I spam clean his posts they will be soft deleted which I don't want because they are spam and I know it.
The only way to see all their posts are trough profile, I see all their posts I see that they are spam but there is no way for me to select all his posts and hard delete them.